As you know, your plant meets most of its needs through photosynthesis. This combines water, carbon-dioxide & light to create sugars. These provide its source of energy. However, they also require access to minute quantities of additional nutrients to help them fight off disease & to build & repair cells. These are potassium, nitrogen & phosphorous. You could think of these as plant vitamins? Without which your plant might continue to live but will never thrive. When free your plant is part of a eco-system through which it can gain access to these micro-nutrients. Sat in its pot it is entirely reliant on us.
When & What?
Plants only require these additional micronutrients when they are in growth & even then in very small quantities. Don't be tempted to over feed as this will lead to a build up of salts in the growing medium. This, paradoxically, will prevent your plant taking up any nutrients at all.
Micro nutrients need to be dissolved in water to be taken up by your plant. There are a number of ways in which to do this. You can add a source of nutrients to your compost mix, top dress in spring or dilute your fertiliser in water & use it throughout the growing season whenever you water your plants. We use worm casts to top dress in spring. This is soil which has passed through a worm's digestive system breaking it down & making its nutrients accessible. These are slowly released over six months or so as you water the plant from the top. It is also organic, doesn't affect the PH of the soil & reduces the risk of salt building up in the soil.
The exceptions
When feeding cacti and other succulents remember the environment they are from where the fertility of the soil is very poor? Over feeding these plants will result in root burn & death. Either buy specialist food or dilute general indoor plant fertiliser to 1/3 of the manufacturers recommended dose. There may be other occasions when you want to add specific nutrients either to the soil or to a liquid feed. This is true when you want to encourage your flowering indoor plants, such as Hoyas, to come into bloom. In this case a fertiliser with additional phosphorous, a so called bloom booster, may help.
So wait till your plants show signs of growth before starting to feed them & when they stop growing, you stop & remember, like most things plant related more is not better :)
Come & see what lovely plants we have on offer? You can buy knowing that what ever your questions about it's care we will have you covered :)
Hi! Please could you tell me more about how to use worm casts? For example, how do I do a thin or thick layer, and how often? Thanks!